1. Field of the Invention
This invention relates to a method and means of determining milk yield from an animal which has been machine milked.
2. Discussion of the Background
Milking machines which separate air and milk flows at the teatcup claw provide one piping system for reticulating the milking vacuum to the claw and another and a separate piping system for transporting the milk away to a receiver vessel or pump. In such milking machinery the milkflow is essentially a single phase liquid flow with relatively little entrained air. With certain designs of such milking systems the milk flow away from the claw is achieved by maintaining the milk system vacuum at a higher level than that which exists within the bowl of the claw and a valve which opens and closes between the two vacuum systems permits the removal of milk from the claw.
It is known to provide a milking system wherein a valve is actively controlled by a level sensing electrode arrangement in the claw being pneumatically operated via a solenoid valve. In other systems it is common practice to provide a valve which is of a float type with the upthrust from increasing milk level in the bowl being used to open and close the valve.
Accordingly to these other similar systems, the milk outflow may usually contain very little air (perhaps less than 5%). If the vacuum differential between the claw bowl and the milk system (typically 15-25kPa) is held constant then the total valve "open time" during the milking of the animal can thus be used (if the milk outflow velocity is constant) to determine the milk yield.